A difficult question is: How do you deal with liars? When an acquaintance, friend, or even family member deliberately lies to you, and you know it, how should you respond? I am not entirely sure what the best response would be, but here are some things that might help.
First, forgive the person. In other words, don't wish harm on the person; don't wish or try to make the person be punished for their lies. We are all human and make mistakes; we are not perfect. So forgive them.
Second, deal with the lie immediately, effectively, and with force. A lie can be extremely damaging and can spread like wild fire. It is your responsibility to expose the lie and kill it before it causes more harm. Forgiving someone does not mean tolerating their nonsense.
Finally, be very careful around a person that has a reputation of being a liar or of hurting people. If you tell such a person a secret, or get close to them, then it is partly your fault if you end up getting hurt. It would be like standing in front of a bus and then complaining when it hits you!